Plasma Electrode Biasing for Monoenergetic Ion Energy Control
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Solution Overview
Problem
The challenge in semiconductor manufacturing is achieving reliable and repeatable plasma processing for high aspect ratio features with precise ion energy control, as traditional RF substrate biasing methods result in bimodal ion energy distributions.
Innovation Solution
A method and apparatus for controlling ion energy distribution in a plasma processing chamber by using a pulsed signal on the upper electrode and a continuous wave signal on the bottom or edge electrode, with power settings below the threshold for plasma excitation to achieve a monoenergetic ion energy peak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional RF substrate biasing methods are used, then plasma processing can be performed, but bimodal ion energy distributions are produced which reduce manufacturing precision
Solution Approach 1:
The patent segments the ion energy distribution control by separating the plasma generation function (continuous wave signal on source electrode) from the ion energy control function (pulsed signal on substrate electrode). This segmentation allows independent optimization of each function, achieving monoenergetic ion distribution without excessive complexity in the overall system.
Solution Approach 2:
The patent applies periodic action by using pulsed signals on the substrate electrode instead of continuous RF biasing. The pulsed signal creates a time-varying electric field that accelerates ions in a controlled manner, producing a narrow, monoenergetic ion energy distribution rather than the bimodal distribution from continuous RF biasing.
2Reliability
If voltage is increased to generate plasma, then plasma formation is achieved, but ion energy control precision is reduced due to bimodal distribution
Solution Approach 1:
The pulsed signal applied to the substrate electrode creates periodic acceleration of ions. During the pulse duration, ions are accelerated to a specific energy; during the off-period, no acceleration occurs. This periodic action results in a narrow energy distribution centered around the pulse acceleration energy, rather than the broad bimodal distribution from continuous RF biasing.
Solution Approach 2:
The patent uses dynamic control of the substrate electrode voltage through pulsed signals, allowing the electric field to be turned on and off. This dynamic control enables precise timing of ion acceleration, creating a monoenergetic peak by ensuring all ions experience the same acceleration window, improving energy precision while maintaining reliable plasma formation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise plasma processing with a narrow, monoenergetic ion energy distribution, facilitating accurate formation of high aspect ratio features in semiconductor devices.
Implementation Method 1
determining a voltage and/or power associated with a bias signal to be applied to a first electrode of a processing chamber, the voltage and/or power being determined based on a pressure inside a processing region of the processing chamber such that the voltage is insufficient to generate a plasma inside the chamber by application of the voltage to the first electrode
Implementation Method 2
applying a second bias signal to a second electrode of the processing chamber, wherein the second bias signal is configured to generate a plasma in the processing region
Implementation Method 3
ions are accelerated from the plasma towards the substrate across a plasma sheath, i.e., region depleted of electrons, formed between the plasma and the surface of the substrate
Data Source
AI summary
Embodiments provided herein generally include apparatus, plasma processing systems and methods for controlling ion energy distribution in a processing chamber. One embodiment of the present disclosure is directed to a method for plasma processing. The method generally includes: determining a voltage and/or power associated with a bias signal to be applied to a first electrode of a processing chamber, the voltage being determined based on a pressure inside a processing region of the processing chamber such that the voltage is insufficient to generate a plasma inside the chamber by application of the voltage and/or power to the first electrode; applying the first bias signal in accordance with the determined voltage and/or power to the first electrode; and applying a second bias signal to a second electrode of the processing chamber, wherein the second bias signal is configured to generate a plasma in the processing region and the first bias is applied while the second bias is applied.